Dehydration system



Feb. 15, 1938. M E

DEHYDRATION SYSTEM Filed April 25, 1930 Inventar Jolzrz III. 6age Patented Feb. 15, 1938 2,1o&259 DEHYDRATION SYSTEM John M. Gage, Los Angeles, Calif., assignor by mesne assignments, to Petroleum Rectifying Company of California Application April 25, 1930, Serlal N0. 447,203

4 Claims.

This invention has general reference to the art of electrically separating substances of differing dielectric values or elec'orical conductances and specific gravities, such as petroleum emul- 5 sions consisting principally of oil surrounding minute particles of water. Such emulsions may also contain, in suspension or solution, solidmatter such as rotary mud, sulphur, and various salts in solution.

According to the usual general practice of separating all such foreign substances from oil, the raw emulsion is fiowed through a treater tank in which is suspended an electrically charged inner electrode, the treater tank being grounded and constituting the unter electrode. The source of electricity connected across the electrodes is the high potential output of a high tension transformer fed by usual alternating current power mains. The wa.ter particles of the emulsion, coming within the influence of the charged elentrocles, are caused to gather into larger arld larger bodies, which finally become sufliciently large to settle by gravity toward the bottom of the tank, where the water is withdrawn. The cleaned 011 rises by virtue of its correspondingly decreased specific gravity, and 1s withdrawn from the upper end of the tank.

It is the general object of the present invention to provide a, method and means whereby the coalescence and settling o1 the water particles may be greatly promoted, to the ends of reducing the percentage o1 water left in the treated oil, increasing the rate of treatment, and generally increasing the efficiency cf the process.

According to the present invention there is provided, a grounded treater tank and an inner live electrode cf comparatively small radius of curvature centrally suspended therein, the emulsion being flowed preferably upwardly through 40 the tank for treatment. The electrostatic field between the inne'r live electrode a.nd the tank is of course at highest gradient near the inner electrode, and grades ofi in intensity towards the tank Wall. The potential applied is of such 45 value that the potential gradient adjacent the inner electrode is sufllciently high to cause active rupture of the 011 films surrounding the water particles in that region, while a1; the same time the gradient at and near the ta.nk wall is 50 below the oil film rupture value. The 011 films in the W gradient zorle adjacent the tank wall 'therefore cannot be punctured, and that mass of emulsion accordingly serves as a high impedance to positively block heavy or disruptive current fiow. 'Ihis impedance consists, in effect,

o1 capacitances and resistances in combination, the reslstance leakage paths being due to free water content. 011 the other band, the relations of the dimensions of the inner electrode, the tank, and the applied potential,are such that 5 a very high potential gradient is obtained adjacent the inner electrode, sufiicient to cause very active rupture of the oil films encasing water particles within that region, with consequeni; coalescence of minute particles to form larger and larger particles.

In the operatlon of the treater, the coalesced wa.ter particles travel, partly by reason of gravity, and partly by other causes which Will appear down the eleetrode until they mach a downwardly directed point on its lowermost end.

The gradient at this point is sufficiently high that the repulsive force between the electrode and the similarly charged water adhering there-v to overcomes the surface tension of the water, 20 and as a. consequence the water is driven downwardly therefrom With great force. Thus the water is driven in good sized particles downwardly thr ough the 011 towards the bottom of the treater, where there is located the 'water 25 withdrawal pipe. 'I'here is thus produced a. heavy streaming of water downwardly from the tapered lower end of the el'ectrode, the downwardly pointing electrode act;ing in the nature Qf an eleetric pump, whieh removes the coalesced water particles from the oi1 in mach less time anti with substantially greater completeness than when gravity alone is relied upon. It is to be noted that it is important that the poixit be directed downwardly rather than laterally, as in certain prior art apparatus since if the particles were driven off horizontally the cleaning action of the electric water pump would be lost entirely, as the water would in such case have 120 settle by gravity alone the same as if the discharge point were not used.

The inventidn will be more fu.lly understood from the following detailed description thereof, reference for this purpose being had to the accompanying drawing, in Which:

Fig. 1 is a vertical section of a dehydrator tank incorporating my improvements;

Fig. 1a is an enlarged view of the lower end of an electrode that has been in use in the process} and Fig. 2 is a. cross-section taken on line 22 of Fig. 1.

Reference is now made to Figs. 1 and 2, in which are illustrated suitable apparatus for carrying out the present process of dehydra- 55 t1on. In the form illustrated, the dehydrator embodies a tank 2l closed a1; the top with a dome 22, and hav1ng a bottom 23. The emulsion supply p1pe 24 1s connected to a, tangentially arranged emulsion inlet 25 prov1decl in the side of the tank, the lnlet belng located preierably somewhat below the lower end. 01 the inner er live electrode 26, hereinafter to be described. The emulsion 1s discharged from 1nlet 25 under a con1cal bafle platze 21 and fiows quietly and more or lass sp1rally upwardly from under its lower edge. A p1pe 28 withdraws separated water from the lower end cf the tank, and another pipe 29 w1thdraws cleaned 011 froxn the upper end of the tank.

An insulator bushing 31 is mounted in the top of the tank, and passing through bushing 3I 1s a conductor 32 which connects 1:0 the upper end of the inner or live electrode 26, this electrode be1ng supported by and extend1ng downwardly below the lower end 01 the bush1ng. The electrode here shown c0ns1sts 0f a. smooth round st'eel rod 0f approximately tw0 and one half inches diameterand, in the present instance, of abot three feet in length. The lower end 013 the electrode is tapered to a po1nt 26a, the tapered point here shown being approximately 10 inches long. The point itself 1s preferably not sharp, but may be rounded t0 a. curvature 0f about one half 1nch, as a. perfectly sharp point produces an intense discharge not suited 1:0 the physical limitations of the preferred apparatus.

With such an electrode, the tank may be in the neighborhood of 10 feet 1n diameter and 20 fest in height, the electrode be1ng mounted in the relative position illustrated in Fig. 1. These proportions and sizes are, 015 course, be taken merely as typ1cal of dimensions wh1ch have been found to be efiective in practice, and the dimensions g1ven are not be taken as limitative 0n the invention.

A conical bafi1e platze 34 about bushing 31 provides a compartment 35 within wh1ch an inert gas may be trapped for protection 01 the insulator bushing against the 011 in the tank.

The upper end 0f the insulator busln'ng 31 is preferably encasecl in an 011 filled housing 40, an insulator bushing 4I serving t0 take a. lead 42 from the bushing conductor 32 outside 0f the hous1ng 40. The 1ead 42 connects to one side of the high tension winding cf a. transformer T the other s1de of the h1gh tension winding'being grounded, as is the dehydrator tank. In a. dehydrator of the proportions described, a potential in the neighborhood of 100,000 to 120,000 volts may efi'ectively be applied 1;he emulsion filled creater.

The treater tank, inner electrode and appl1ed potential be1ng thus relatively proportioned, there is established adjacent the electrode a high potential gradient, sufficient to cause very active attraction between the water particles and rupture of the 011 films surrounding the water particles, while at and near the tank Wall the gradient 1s below the 011 film rupture va1ue, there being thus an outer zone of emulsion adjacent the tank Wall wherein no 011 film breakdown 0ccurs; and Which serves as a high impedance of cgmbined capacitances and resistances 130 prevent shor1; circuitirig currents between the-electrodes.

In the operation 0f the system, the infiowing emulsion, usually preliminarily heated, rises from inside the edge of baffle 31 up the s1des 0f the tank, and towards the inner electrode. During auch travel the 011 film encasecl water particles pass thr0ugh a field 01 higher and. higher grad1- ent, until a1; or near the inner electrode the gradlent is sufliciently high 120 cause rupture of the 011 films and coalescence of adjacent; water particles. Upon reaching the inner electrode, the 011 films may be broken, permitting the water to web the electrode. The water 1s then 01 the same charge as the electrode and is in consequence subjected to a repulsive force-, but may be prevented from 1eaving the upper larger diameter portion of the electrocle because of surface tension. The water then travels down the electrode rod by gravity, and by other forces wh1ch will appear, t0 the lower tapered end thereof. At the point 0f the electrode the gradient. is sufl1- c1ent to overcome the adhesion of the water, and the water is dr1ven downwardly therefrom with great force. This downwardly rushing waterprojected from the point also picks up additional water adjacent the p01nt and carries 1t downwardly by je1; action, as in the familiar steam injector. It will also be seen tha.t this downward projection of weiser from the polnt of the electrocle aids in dragging the water particles adher- 1ng 120 the upper portion of the electrode down to the point thereof for downward projectlon.

It 1s particularly to be noted that the drive of the charged water part1cles from the electrode is directly downward, and that the effect of the electrode po1nt is thus to act, along with the f0rce of gravity, 120 force the water particles downwardly through the 011, thereby greatly hastening the collecti on of the water in the bottom cf the treater. This downward propulsion 0f the water also tends to set up a general closed circulation of 1;he liqu1ds laterally inward toward the electrode, downwardly from 1ts po1nt, and around and back up the treater s1de walls (see F1g. 1). Of course, this circulation of the liquids is n0t due to electric action on the water particles alone, but the motion of the water part1cles through the 011 tends by frictional drag to Set up a slow ring-circulation of the oil such as Indicated. in F1g. 1. The water particles themselves tend 110 fall 0r be driven down and out of this ring, while the 011 r1ses in the general circulation adjacent the treater side Walls, perhaps still carrying a percentage of water for a second trip 1aterally to and downwardly from the electrode; but the larger water particles continuously fal1 out of the circulation a1; the 10W point 0f the circulation ring and rapidly collect in the botto of the treater for withdrawal.

The cleanest and dryest 011 is that which rlses in the centreil portion of the treater about the electrode, and this 011 fiows 01112 of the treater by way 01 the path between the unter surface of cone 34 and the inner surface 0f a baflle plate 46 that incl1nes downwardly from the inside wall 01 the tank, as shown, the cleaned 011 being finally delivered from the tank by means 01 pipe 39. The baflle 46 deflects the rising 011 and prevents o1l closely adjacent the side Walls 0f the treater from rising 120 the 011 outlet, which 1s desirable since 011 rising at t-he s1de Walls cf the tre ater might n0t be fully dehydrated due t0 its distance from the inner electrocle. Fig. 1a shows an electrode wh1ch has been m use for a considerable length of time. The upper cylindrical portion of the 2 inch electrode and the point, down 10 where the point is about 1 inches in diameter, are black from the 011. From Where the point is 1 inches in diameter, however, the black grades off unt1l the lower t1p 01 the polnt 1s hlghly polished. 'Ihls lower pollshecl rising immediately inside seid tank toward seid.

tip is the portion of the point from which the water particle discharge takes place, and above the polished tip is the portion of the electrode which acts to coalesce water particles laut froxn which there is 'no such discharge.

And in this connectzion lt is tso be pointed out that while the t;ip on t:he lower end of the electrode is herein and in the appended claims' referred to as a point, that; this point may be rounded or haue any conflguration desired so lang as t he gradient at the end reiaches' a. aufliciently high value to throw cf]? the water.

It will be recognized that the illustrative system specifically described herein is capable o! considerable modification and rearrangement; withoui; departing from the spirit and scope o1 my invention; and lt; is therefore to be understood thai: the following claims embra.ce all such modifications and equivalent arrangements es may fairly be construed to feil within the scope oi my invention.

I claim:

1. In combination in an electric treater for emulslons: a tank providing top und bottom members cooperatqing in defining a chamber; und means for setting up a ring circulation in said tank which is upward immediately inside said tank and downward in the central portion of Saul tank, said means including central live electrode extending downward in seid tank und a. batile platze extending inward from said tank below seid top member for deflecting inward toward said live central electrode any emulsion baflle plante.

2. A combination es deflned in claim 1 in which seid baille platze is annular and of frustro-conical shape.

3. A combination as defined in claim 1 including an apron extending downward in the upper end of seid chamber above said batlle platze t o form a compartment and providing an edge dlsposed vertically above said baflle platze, said edge cooperating with said tank in providing an annular space through which the lighter phase liquid of sa.id emulsion may rise, and including means for withdrawing this lighter-phase liquid from said tank at a positlon above said edge, and including an insulating means supporting said live electrode and disposed in said compartment.

4. In combination in an electric treater for emulsions: a. tank; electrode means including a. live electrode in said tank for est;ablishing an electric field therein; an aproxi extending downward in the upper end oi said tank und providing a compartment; insulator means in seid compartment for insulating seid live electrode from seid tank; means for withdrawing liquid from the space between said tank and said apron; and deflector means extending inward from said tank at a level below said apron to deflect any stream of rlsing liquid from flowing directly into the space between said tank and seid apron.

JOHN M. CAGE. 

